In mild cases, this inflammation can cause a cough and a sore throat, but in severe cases it can escalate, “essentially stopping oxygen from reaching your blood”, Professor Gupta adds.

Even in non-fatal cases, this can still be extremely unpleasant.

At the beginning of March, 29-year-old Daryl Doblados was well enough to run the Cambridge Half Marathon. Just two weeks later he was being rushed to hospital because his lungs felt like they were “filling up with smoke or liquid”.

In a video posted on Facebook, he said: “I struggled to breathe. I’ve never experienced anything like this before.”

What do we actually know about Sars-CoV2?

Very little compared to other coronaviruses. simply because it’s only been around for a few months.

Because of this and also due to the varying ways cases in different countries are recorded, the fatality rate for Covid-19 is still being worked out by scientists. Current estimates, though, put it at around 1.3% of cases.

Are older people always more at risk?

No. During the so-called Spanish Flu outbreak, up to 50m people died between 1918 and 1919. In an almost a total reversal of what the world is seeing now, 99% of the deaths recorded in the US, for example, were aged under 65.

And on April 2 it was revealed that, of 44 coronavirus patients without underlying health problems who had died, one was just 27.

So... why are they dying?

The simple (but frustrating) answer is that we just don’t know for certain – it’s just too early to tell.

One possible theory concerns something called a “cytokine storm” where a healthy patient is essentially killed by their own, overreactive immune system.

“For some reason these viruses are setting up uncontrolled inflammation,” says Professor Gupta. “The body’s immune response becomes the main problem in that it becomes over-inflammatory.

“That may be one of the reasons why young people sometimes become very sick and die – because they have very strong inflammatory responses to the virus.”

What causes this response in some people but not others?

Again, we just don’t know at this stage. “It may be due to genetics or other infections they’ve encountered in the past – we don’t really understand what’s causing this,” says Professor Gupta.

“I think by the end of the year we’ll have a lot more information about what’s going on.”

Will we have a treatment?

While the ultimate prize to get the world through the coronavirus pandemic is a vaccine, there are drugs being trialled that may help those suffering now.

There is currently no approved treatment for Covid-19 and companies and doctors have been hunting for a drug already approved and in production to help keep thousands more patients from dying than standard care alone.

Those that target the excess inflammation caused by cytokine storm could be promising, meaning a number of arthritis drugs are currently being trialled.